Undercutting earth auger



Oct. 7, 1952 R. A. RANSDALL UNDERCUTTING EARTH AUGER Filed Oct. 51, 1949 s Sheets-Sheet 1 IN VEN TOR.

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Arm/yer Oct. 7, 1952 Filed 001;. 51, 1949 R. A. RANSDALL UNDERCUTTING EARTH AUGER 3 Sheets-Sheet 2 INVENTOR.

Patented Oct. 7, 1952 UNITED STATES PATENT OFFICE UNDERCUTTING EARTH AUGER Ralph A. Ransdall, SanFranci sco, Calif. Application October 31, 1949; Serial No. izitiio i i 1 My invention relates or boring holes in material especially: earth and is concerned largelywith an earth auger, usubore so that concrete or other placement material will have a secure interengag'ementwith the earth and will provide a firm support and foundation for the structure.

It is therefore an object of my invention to provide an earth auger effective to undercut a chamber.

Another object of my invention is to provide an undercutting earth auger automatically efiective adjacent the bottom of the hole to-provide an enlarged chamber.

A further object of myinvention is to provide an undercutting earth augereasily introduced into a hole previouslybored by a suitable tool and as easily withdrawn from the here after the undercutting has been accomplished. t

A still further object of thy-invention is to providean undercutting earth auger useful with the power driving mechanisms generally available.

A still further object of my invention is to provide means for driving the cutting device in' an undercutting earth auger at-various distances from the rotational axiswi'thout undue strain on the driving and setting mechanisms.

drical earth bore showing in side elevation my earth auger therein. v Figure 2 is a view comparable to Figure 1. but

showing the cutters in an extended position.

Figure 3 is a plan of the structure shown in Figures 1 and 2, a partoi the driving shaftbeing disclosed incross section and apart of. the figure being broken away to reduce its size.

Figure 4 is a cross-section the planeof which is indicated by the line 4-4 of Figure 3.

Figure 5 is a detailed side. elevation of the structure ,shownin Figure 4-but-,with parts or- 8 Claims. (01. 25544) to means for providing adjacent the bottom of a bored hole to provide 2 thecentrally located melianism broken away to disclose the intiior construction, particularly the teetn.

Flgl'lifi is" across sect-ion the plane of which is mdicateoby a line t -tor Figure 4.

Figure 7 is a cross-section the planes of which are indicated by the-lilies 1'-"! of Figure 4.

Figure 8 is a fragmentary cross-section on an axial plane showing the detailed arrangement cially designed and depending also upon the environment in Whidli it is utilized, it has successfully been incorporated in the form shown herein. oustomarily, a standard form of earth auger fiiS't Used to provide" a bore 6 in the earth L the bore having a uniform, circular cylindrical cross-section In the beginning of the undercutting operation, my undercutting earth auger is disposed a position approximately asilliistrated in Figure 1. nism is located within the bore 6 coaxially with the axis 8 of a driving shaft 9 extending from a suitable source of'rotatio'n or driving power, not shown, usually located at or above the surrace of the earth T. Theshaft 9 is preferably square in eross section and at itslower end is provided with acir'cular portion ll fitting within asleeve I2 forming part of adriving tube 13. Also included the driving tube I3 is a pilot sleeve surrounding the short end of the shaft.

The inteieng'agement between the tube l3 and 1theshaft 9 is further efieotuated by a cross pin and of axial translation in unison.

An additional object of my invention is in At the bottom, the driving tube l3 ends in a flange 11 receiving fasteners l8 for securing the driving tube to a cros'shead l9. The crosshead is a rather massive" block-like structure disposed symmetrically with respect-to the axis 8 and includes acentral web 2'0 a top plate 2|; and a bottom plate These are closed at the sides by' removable olosure plates 23 and 24 held on by fasteners 26'. The web 20, the top andbottom plates 21 and 22 and the closure plates 23 and together defineapair oi transversely extend ingch-annels 21 and 28re'spectively (see Figures 6 and 7); liiachor these; channels is rectangular or preferably square in transverse cross-section and each of them is-arr'angedso that its central axis 29 or 3| is horizontal. The axes 29 and 3i are, parallel to: each other and are approximately radial with respect tothe axis 8 although they are spacedpso thatthe axis 8 extends between-them... The axes 2'9 and 3i are likewise both-containedin. a plane normal or perpendicuulantoz: the: rotational and' translational axis 8.

28 there is disposed a cutter carrier 34.

vided with an extension 36 (Figure 7) conveniently welded thereto and extending through an opening 37 in the bottom plate 22 of the crosshead. Reinovably secured to the extension 36 by appropriate fasteners 38is a cutter 39. This is of any suitable sort for working in earth or comparable material and preferably includes abeveled plate carrying a hard facing material.

The cutter carrier 33 is similarly provided with a cutter ll of a type usually comparable to that of the cutter 39 although the two cutters may have differences between themselves. Both cutter carriers are freely slidable within their channels.

It is intended that the cutter carriers be moved equally and simultaneously in radially opposite directions, either so that they can both be retracted together or so that they both can be extended together. carrier 33, for example, is provided on an interior For this reason the cutter face with a group of series of rack teeth 42, the z teeth being disposed at a predetermined or selooted direction of inclination. comparably, the

cutter carrier 34 is provided with a groupor series of rack teeth 43 but the inclination of these teeth is oppositely disposed to that of the teeth 42 as especially shown in Figure 5, for example. I

Adapted to mesh with the teeth 42 and 43 are correspondingly inclined teeth 44 and 45 on a plunger 46 disposed coaxially with the driving tube i3 and extending into and designed to slide.

through the crosshead [9. With this arrangement, translational movement of the plunger provides corresponding and oppositely directedradial movement of the cutter carriers 33 and 34. The plunger preferably is rectangular in crosssection and in addition to its other support is guided for translational movement by a guide.

tube at forming part of and extending from the lower plate 22 of the crosshead.- Not all ofv the plunger 38 is provided with teeth. The remaining portion is smooth or plain and a packing mechanism 5| (see Figure 8) is provided to ensure that earth and otherdeleterious material is kept out of the sliding inter-connection. The packing 5! is renewable by removal of a securing plate 52 normally held in position by a screw 53.

- Since the plunger 4% is square, there are four packing structures 5i provided, one on each side.

Normally, it is desired to keep the cutter carriers retracted so that I provide a means for this purpose. Conveniently that means takes the form of an elongated coil spring 54 disposed withrecess Within the plunger so that the plunger is urged to project from the guide tube 49. The inclination of the teeth 44 and'45 being appropriate, the cutter carriers are in this fashion retracted firmly against adjustable stop screws 59 at opposite ends of the crosshead, the screws being retained in adjusted position by appropriate nuts 6i. The structure is held to an adjustable minimum envelope diameter when the cutters are withdrawn.

While the cutters are normally retracted as the mechanism is introduced into the bore 6, it

is desired automatically to extend such cutters when the bottom of the bore has been reached.

For that reason I provide at the lower end of the plunger 46 an abutment plate 62 mounted for rotation relative to the plunger. Since the plunger itself is rotatable about an axis and since the. abutment plate 62 is rotatable with respect to the plunger ibis feasible tohold the abutment plate stationarily against the earth I while the remaining part of the structure revolves. The abutment plate 62 .is mounted on an anti-friction bearing 53 appropriately retained at the bottom of the plunger it. An efiectiveearth seal 64 prevents the entry of foreign matter to the bearing. A centering and guarding cone tip 66 not 7 only forms an appropriate housing for the bearing but likewise assists in centering the structure in the bore 6.

When the mechanism is lowered into the bore and the weight of it comes upon the plate 62 as the plate engages the subjacent earth 1, the plunger is driven into the crosshead, or considered oppositely, the crosshead descends to telescope the plunger into the guide 49. This relative movement of translation projects both of the cutter carriers 33 and 34 to their maximum extent. Since this action of projecting the cutter carriers can occur and usually does occur progressively as the crosshead is lowered, the cutters extend radially outward at an inclination to the axis 3 depending upon the inclination of the driving teeth, s4 and 45, especially as illustrated in Figure 2. As the cutters descend, the diameter of the excavated hole is enlarged and the remainder of the earth is'undercut. The sleeve 49 covers-more and more of the plunger 46 until the bottom of the stroke has been reached. At that time the weight of the mechanism is removed from bearing upon the plunger and the plate 62 and the spring 54 is then effective during the upward movement of the crosshead to project the plunger from the guide tube 49 or, considered conversely, to lift the crosshead from the plunger. Due to the inclination of the driving teeth 44 and 25, the two cutter carriers are retracted to their original position having an envelope diameter not greater than that of the bore 6. In this fashion the undercut is made and the auger is withdrawn.

Since the cutter carriers are relatively close fits within their channels, I provide a means for preventing the entrapment of air. or of foreign material within thechannels 21 and 23. Lubricant is also present in contact with these parts andtends to displace as they are moved. For these reasons, as especially shown in Figure 6, each of the channels is provided with a conduit H leading to a cross bore 72. The cross bore merges with passages :3 extending through the upper plate 2| to the interior of the drive tube 13 so that communication is established between them and with the drive tube l3 atmosphere. Lubricant and air can consequently interfiow freely as the cutter carriers retract and project, so that excess pressures or partial vacuums cannot occur. Disposed on the upper surface of the crosshead are appropriate hand grips 74 so that the tool can be manipulated readily, can be started in position and can be manually rotated while it is being adjusted initially or retracted finally from the earth.

Iclaim:

1. An undercutting earth auger for use in a hole having a central axis comprising a crosshead, means for supporting said crosshead for rotation about said axis, a cutter carrier, means for supporting said cutter carrier in said crosshead for movement approximately radially of said axis, a cutter on said cutter carrier, means for urging said cutter carrier toward said axis, and earth engaging plunger mounted in and depending from said crosshead for movement along said axis, and means interconnecting said plunger and said cutter carrier for moving said cutter carrier away from said axis upon upward movement of said plunger along said axis.

2. An undercutting earth auger for use in a hole having a central axis comprising a crosshead, means for supporting said crosshead for rotation about said axis, a cutter carrier, means for supporting said cutter carrier in said crosshead for movement approximately radially of said axis, a cutter supported on said carrier, in clined rack teeth formed on said cutter carrier, an earth engaging plunger mounted in and depending from said crosshead for movement along said axis, inclined rack teeth on said plunger meshing with the inclined rack teethon said cutter carrier, and a spring efiective to project said plunger downwardly along said axis and through said meshing teeth to retract said outter carrier toward said axis.

3. An undercutting earth auger for use in a hole having a central axis comprising a crosshead, means forsupporting said crosshead for rotation about said axis, a pair of cutter carriers, means for supporting said cutter carriers in said crosshead for movement approximately radially of said axis, cutters supported on said cutter carriers, inclined rack teeth formed on said carriers, an earth engaging plunger mounted in and depending from said crosshead for movement along said axis, oppositely inclined rack teeth on said plunger meshing with the respective inclined rack teeth on said cutter carriers, and a spring effective to project said plunger downwardly along said axis and simultaneously to retract both of said cutter carriers toward said axis.

4. An undercutting earth auger for use in a hole having a central axis comprising a crosshead, means for supporting said crosshead for rotation about said axis, a pair of cutter carriers, means for supporting said cutter carriers in said crosshead for movement approximately radially of said axis, cutters on said cutter carriers, a plunger mounted in said crosshead for movement in both directions along said axis, means interconnecting said plunger and said cutter carriers for simultaneous positive move ment in both directions with respect to said crosshead, and an earth engaging abutment plate mounted for rotation on the lower end of said plunger.

5. An undercutting earth auger for use in a hole having a central axis comprising a crosshead, means for supporting said crosshead for rotation about said axis, said crosshead having a channel therein arranged with the channel axis spaced from said rotational axis and in a plane normal thereto, a cutter carrier movable in said channel, a cutter on said cutter carrier, inclined rack teeth on said cutter carrier, a plunger 6 mounted in said crosshead for movement along said axis, meshing rack teeth on said plunger, and means for moving said plunger along said axis and through said meshing teeth for moving said cutter carrier in said channel.

6. An undercutting earth auger for use in a hole having a central axis comprising a crosshead having a pair of parallel channels therein, a pair of cutter carriers slidable in said channels, means for rotating said crosshead about said axis between said channels, a plunger mounted in said crosshead for movement along said axis, meshing rack teeth on said plunger and on said cutter carriers for imparting simultaneous sliding movement to said cutter carriers as said plunger moves along said axis, an earth engaging abutment plate rotatably mounted on one end of said plunger for use in moving said plunger in one direction, and a spring interposed between said crosshead and said plunger for urging said plunger in an opposite direction.

7. An undercutting earth auger for use in a hole having a central axis comprising a driving shaft adapted to be rotated about said axis, a crosshead, a drivingtube on said crosshead and engaging said shaft, a guide tube on said crosshead, said tubes being disposed along said axis, a pair of cutter carriers means mounting said cutter carriers in said crosshead for approximately radial sliding movement on opposite sides of said axis, cutters on said cutter carriers, a plunger slidably mounted within and projectable from said guide tube, means interconnecting said cutter carriers with said plunger for sliding movement in opposite directions as said plunger slides within said guide tube, and a spring for urging said plunger into a position projecting from said guide tube.

8. An undercutting earth auger for use in a hole having a central axis comprising a driving shaft adapted to be rotated about said axis, a crosshead, a driving tube on said crosshead and engaging said shaft, a guide tube on said crosshead, said tubes being disposed along said axis, said crosshead having a pair of channels square in cross section and extending approximatelw radially of and on opposite sides of said axis, a pair of cutter carriers square in cross section and slidably disposed in said channels, inclined rack teeth on said cutter carriers, a plunger slidable in and projectable from said guide tube along said axis, oppositely inclined rack teeth on said plunger respectively engaging said teeth on said cutter carriers, an earth engaging abutment plate rotatably mounted on one end of said plunger for use in moving said plunger into said guide tube, and a spring engaging said plunger for urging said plunger into a position projecting from said guide tube.

RALPH A. RANSDALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,643,572 Black Sept. 27, 1927 1,764,133 Weisgerber June 1.7, 1939 1,822,216 I-Iartson Sept. 8, 1931 1,878,260 Bunker Sept. 20, 1932 1,887,895 Sipe Nov. 15, 1932 1,993,948 Schroeder Mar. 12, 1935 2,012,774 Roe Aug. 27, 1935 

